#include<iostream>
#include<string>
#include<algorithm>
using namespace std;

class Solution
{
public:
	string addStrings(string num1, string num2)
	{
        int end1 = num1.size() - 1;

        int end2 = num2.size() - 1;

        string strret;
        int carry = 0;
        while (end1 >= 0 || end2 >= 0)
        {
            int val1 = (end1 >= 0) ? (num1[end1] - '0') : 0;
            int val2 = (end2 >= 0) ? (num2[end2] - '0') : 0;

            int ret = val1 + val2 + carry;


            carry = ret / 10;

            ret = ret % 10;

            strret += ('0' + ret);

            end1--;
            end2--;
        }
        if (carry > 0)
        {
            strret += ('0' + carry);
        }

        reverse(strret.begin(), strret.end());
        return strret;
	}
};

